stupid allen head screws on Eagle Alloy Mag center caps

The recommended anti-seize for ss in aluminum, marine duty (think outboard) is zinc filled. I've got a can of the Loctite version. The stuff's expensive, but might be worthwhile in Ontario. I guess your roads are saltier than the sea.
Pete Keillor

Vehicle hardware is exposed to nasty environmental factors (like marine hardware). For a number of years now, any time I replace vehicle or outdoor hardware I'll apply a generous amount of blue Loctite to the threads. If the threads are full of something waterproof, then water isn't going to be able to migrate into the thread gap.
This will prevent a lot of frustration/fastener anxiety when they need to be removed again. This has also been working well for dissimilar fastener metals.. the corrosion needs an electrolyte in contact with the metals, generally water or moisture. If the electrolyte is kept out, the corrosive action is prevented from occurring.
FWIW, Loctite threadlocker products are now available in stick (like a chapstick) and roll-of-tape versions of the traditional red and blue liquids.

These wheels will never again see salt. I think they saw one or two winters with the original awner.

When I was doing systems engineering at FLIR one of the manufacturing guys caught me using a button-head allen screw to put together a test jig. He informed me in quite definite terms that I would be an Unhappy Design Engineer if I ever specified such a fastener to be used in production.
Happily, I was able to tell him that I had less than zero authority or even influence in what fasteners actually made it in mechanical drawings, and I was just using up fasteners from the discard pile. The idea that I was removing such fasteners from circulation made him happy.
I wonder if anyone makes flat-head to cap screw adapter washers? That might be a good solution for you -- you could use nice looking socket- head screws with nice big sockets, and not munge up the holes in your caps.

I like a straight silicone grease to keep the moisture out.

McMaster has some nice flat head Torx and pin-spanner options.

Wow, I thought I was the only one that thought that. xD
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Back in the 70's and 80's they sold expensive sets of Allen screws so a guy could replace all the #3 Phillips head screws on the Jap dirt bike engines.
I never had any trouble with the original #3 Phillips heads. xD
I first used a 3/8" punch and hammer and flatten the head just a little and then hammer the #3 screwdriver into the head with a -perfect- fit. LOL :) All that hammering would make 'em come right out easy as anything. Over and over for years and years too, still got my 4 stroke cattle-trail'er and the trick still works that way on it just like it did 35 years ago. xD
Alvin in AZ

I love Torx....

I'm with you. I've never been pleased with allen head screws. Few people think to Never Sieze or grease the threads. The pins on GM front brakes can be a nightmare.
On GM, a friend of mine "doesn't like" the tall lug nuts that Buick provided. So, he bought small acorn nuts from the auto store. I advised this is a bad idea. Well, they fused to his aluminum rims. The acorn nuts aren't tall enough to get a bite with any kind of wrench. He ended up wearing them off with a long nose grinder (which he borrowed from me). That took many hours. Act in haste, repent at leisure. . Christopher A. Young Learn more about Jesus . .
I had some fun this evening - removing the bolt-on center caps from my Eagle Torque Thrust style mag wheels. Like the "original" American Racing Torque Thust, the cap fastens with 5 screws. Eagle usis countersink head screws with a tiny allen socket in them (3/32 inch?)- and those buggers had been in there for over 10 years and had no intention of coming out without a fight. Ed's Red, a propane torch, hammer and punch - all judiciously applied over a 2 1/2 hour period finally got all 20 out!! Now to finish stripping them, clean up the corrosion that was under the paint, alodyne the centers, and repaint them - and polish and detail the caps. NOT using those stupid little allen head screws again if I can find an alternative!!!.

I'll likely use Philips head screws in place of the tiny allen socket heads.

I suspect the pin spanner units would be just as problematic - and what size Torx do they use on a #8 screw? Likely almost as silly as the allen.

to Never Sieze or grease the threads. The pins on GM front brakes can be a nightmare. So, he bought small acorn nuts from the auto store. I advised this is a bad idea. Well, they fused to his aluminum rims. The acorn nuts aren't tall enough to get a bite with any kind of wrench. He ended up wearing them off with a long nose grinder (which he borrowed from me). That took many hours. Act in haste, repent at leisure. Strangely GM caliper pins have NEVER given me trouble.

I have removed many a stubborn screw by cutting a slot with a small fiber wheel then using an impact screw driver with a common tip. I've done it so many times I buy the bulk packs of the small fiber wheels to use in my rotary hand piece.

I hate Phillips FAR more than Allen. Worst: those damn tiny ones on the PAR36 headlight retainer rings. As Moosewacker used to say: Drill Baby Drill...

In another lifetime, I used to use wheel bearing grease as anti-seize. Now, with more experience , I prefer the aluminum type of anti-seize.
R&R the little bolts at the time of the original purchase of the rims next time, eh? Preclude the corrosion by doing them when new. I wish the wheel mfgrs did that as a best-practice, don't you?

I live in NYS, where the highway department puts road salt down with a passion. Not sure if the salt mine in Retsof, NY is still active. But, they salt the roads generously. Vehicles rust out, early, here. . Christopher A. Young Learn more about Jesus . .
Strangely GM caliper pins have NEVER given me trouble.

T15 Torx on the stainless 8-32 flat head screws. About $12 for a pkg of 50.

Impossible to do in this case without ndamaging the $50 center cap.

The philips in this case is a real #2 philips head - so no problem at all. If it partly seizes, put a philips bit in the impact driver and swat it with a hammer - out it comes.
Or use a Posi-Drive bit.